United States Patent | 5,391,329 |
Dougherty, et. al. | Feb. 21, 1995 |
Inventors: | Dougherty; Thomas K. (Playa Del Rey, CA); Elias; William E. (El Segundo, CA); Kost; Alan R. (Woodland Hills, CA); Klein; Marvin B. (Pacific Palisades, CA). |
Assignee: | Hughes Aircraft Company (Los Angeles, CA). |
Appl. No.: | 109,884 |
Filed: | Aug. 23, 1993 |
Intl. Cl.: | B29D 11/00; |
U.S. Cl.: | 264/1.7; 156/228.; |
Field of Search: | 1.7;2.7;320;325;1.9;1.1;216 |
3,582,424 | Jun., 1971 | Norvaisa | 156/245 |
4,360,483 | Nov., 1982 | Ayres | 264/ 2 .7 |
4,659,407 | Apr., 1987 | Lacotte et al. | 156/228 |
4,878,973 | Nov., 1989 | Ohtake et al. | 264/ 1 .7 |
5,080,469 | Jan., 1992 | McCahon et al. | 359/241 |
5,172,278 | Dec., 1992 | Tutt et al. | 359/885 |
Primary Examiner: Vargot; Mathieu D.
An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.
This invention was made with United States Government support under Contract No. N62269-90-C-0239 awarded by the Department of the Navy. The United States Government has certain rights in this invention.